Epicuticular Wax of Norway Spruce Needles as Indicator of Traffic Pollutant Deposition

Author: Viskari E-L.  

Publisher: Springer Publishing Company

ISSN: 0049-6979

Source: Water, Air, and Soil Pollution, Vol.121, Iss.1-4, 2000-07, pp. : 327-337

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Abstract

Two-year-old Norway spruce (Picea abies (L.) Karst) seedlings were exposed to traffic emissions along roadsides with three different traffic densities and speed limits; highway, street and a quiet local road. Deposition of the polyaromatic hydrocarbons (PAH) was determined at all sites using moss bags as an indicator of organic traffic pollutant deposition. Short term concentrations of atmospheric nitrogen oxides (NO_x) and aerosol black carbon (BC) were also recorded from the sites. The responses of the needle epicuticular wax structure of the exposed spruce seedlings were analysed under the scanning electron microscopy (SEM). The epistomatal wax structure of needles was distinctively fused and aggregated along the highway and street with relatively high traffic densities. Along the local road, where the traffic density was low, no significant degradation of needle epicuticular wax was observed. The NO_x and BC data, along with PAHs accumulated in moss bags indicate significant deposition of gaseous pollutants and particulate organic compounds along the highway and street and these are suggested as cause of the epicuticular wax degradation. Epistomatal wax structure is thus suggested to be an early indicator of traffic exposure effects.